Intermittent kompressor, advice please.

[Dieselman]

The purge valve takes all those nasty bezine fumes that build up in the activated charcoal cannister, and sucks them into teh engine to be burnt and processed by the Cat.

Thinking about the problem of the compressor, what is probably happening is that the MAF is supposed to detect the operation of the purge valve at idle condition due to the amount of air being drawn via the MAF reducing when the purge valve operates.
If the MAF can't detect the purge valve for five consecutive operations then the ECU goes into limp home mode and drops the charger clutch as a safeguard.

A similar effect is found on diesels if the EGR valve isn't working, again checked via the MAF reading.

Good find BigD

 

[BigDusty]

Thanks Dieselman and for the info, making sense now.

My car is running spot on. Worth all the trouble because as I mentioned before I do love a challenge (providing it's not to expensive), and the more prodding and probing I do the more I get to know about my car, this is my first Mercedes and I have to say, complicated as it may seem I'm definitely a huge fan.

Cheers,

BigD.

 

[GrahamC230K]

What a great result.

 

[1998K]

In the Haynes manual they say that the Activated charcoal canister need a sort of maintenance with a defined schedule!
Not well specified the requested operations! Sort of cleaning!?

but I've never done/heard someone have done it

 

[BigDusty]

In the Haynes manual they say that the Activated charcoal canister need a sort of maintenance with a defined schedule!
Not well specified the requested operations! Sort of cleaning!?

but I've never done/heard someone have done it

Your right, Checked my Haynes and it says that every 30,000 miles or 2 years the "Evaporative emission control charcoal canister" should be renewed, does not say anything about cleaning it as it doesn't look possible.

Thing is, I have looked through all the receipts for all the services my car has had (and there are loads and 95% by MB) and I can't seem to find any info on this part ever being change.

I wonder how important it is to the running of the car and how much would one cost to replace.

 

[BigDusty]

I've been driving around today and started to notice the car missing again and suffering from lack of power but this time the kompressor was still working. Anyway, got back to my place and had a look under the bonnet and the purge valve was ticking again. Checked the connections and rubber pipes and they seem fine, turned of the engine started it back up again, ticking gone. Took her for a spin, OK for a moment then started to misfire. Checked the valve and yes you guessed it ticking again.

What I decided to do, I pulled off the rubber pipe from the throttle unit and sealed it up (sealed the bit that sticks out of the throttle unit not the rubber pipe) and went for a spin. The car acted normal with no misfiring and with plenty of power and the kompressor kicking in as it should.

I'm not to happy with leaving it like this but I have a new purge valve on order, so I'm hoping that this part is faulty and will solve my problem when I fit the new one.

The thing is, can anyone tell me if I could be doing any damage to the car by driving it with the purge valve disconnected and the pipe sticking out of the throttle unit blocked? MB informed me that the valve will take about a week to arrive.

BigD.

 

[Bazzle]

The valve is suposed to tick, as it "purges" fumes from the cannister at idle.

Bazzle

 

[BigDusty]

The valve is supposed to tick, as it "purges" fumes from the canister at idle.

Bazzle

I suppose it would tick but how loud and how often? Should it stop ticking when at high revs (which it doesn't) and why does my car run better when I disconnect it from the throttle valve and block up the throttle end.

BigD

 

[1998K]

sorry to couldn't be able to help you more, but probably it's correct that the valve stop working at higher revs; better if you ask to the Dealer (hoping to find a decent technician!).

as far as the "Evaporative emission control charcoal canister" I made the same question you have! Never found any info how to perform maintenance to this device.

 

[BigDusty]

sorry to couldn't be able to help you more, but probably it's correct that the valve stop working at higher revs; better if you ask to the Dealer (hoping to find a decent technician!).

as far as the "Evaporative emission control charcoal canister" I made the same question you have! Never found any info how to perform maintenance to this device.

Been in contact with MB and even though they don't replace the canister that often they have advised me to renew mine because if it is the original then it should be changed, specially if my car has done over 200K miles. After so much usage it can get choked up and cause back pressure (so they told me). They have one on order for me and I will be interested to see this canister, how it works and the condition of my old one and to see if it makes any difference to the car.

Still looking into it.

MB are also very interested in my find with the performance problems caused by this valve and the fact that the car is running much better without it connected. They also want me to inform them of my results when I fit a new one.

BigD.

 

[1998K]

Hey BigD.

thanks for keep us informed.

Hope you'll find as soon the solution!

Hi

 

[Dieselman]

MB are also very interested in my find with the performance problems caused by this valve and the fact that the car is running much better without it connected. They also want me to inform them of my results when I fit a new one.

BigD.

Now that information just has to be worth something. It's taken you how long x £100 per hour to work it out.

 

[BigDusty]

Now that information just has to be worth something. It's taken you how long x £100 per hour to work it out.

Now that's a thought, what did I do with that calculator?

 

[BigDusty]

Thought I'd give an update and conclusion to this Kompressor problem, sorry it's been so long but I wanted to be sure that everything was working fine.

I replaced the purge valve and carbon canister back in February and touch wood my car seems to be OK. The Kompressor has not once failed and idling is smooth as can be.

I have informed Mercedes (without charge) of my findings and they have now made a note of this for future diagnostic purposes.

Cheers
BigD.

 

[1998K]

Hi BigD.

nice to see you again, ... as you said touching wood (here we call touching iron) thanks for your contribute!

Marco

 

[GarethM]

Big D

So does the new purge valve tick ? ( How much was a new one ? And how much was a new canister ?

Im intreged as mine ticks ( sometimes ! ) ? ( Only had the car a few weeks and still learning )

Cheers

G

 

[Glenn Smith]

very interesting thread, have been wandering for some time as to the air recirc flap and what it does, my guess is it acts as a boost control valve come dump valve to prevent overboost during the overrun also is it open or closed during idle up to the point the supercharger kicks in, anyone know? no problem on my car but like to know what it all does and can't find any info anywhere.

 

[Bazzle]

very interesting thread, have been wandering for some time as to the air recirc flap and what it does, my guess is it acts as a boost control valve come dump valve to prevent overboost during the overrun also is it open or closed during idle up to the point the supercharger kicks in, anyone know? no problem on my car but like to know what it all does and can't find any info anywhere.

This is how I see it working on pre 2000 230 engines with clutch on supercharger.
Valve opens at idle so air can get to engine as supercharger will block path whilst not turning.
As load on engine increases and clutch operates flap closes to allow boost to engine. Flap will open a bit to vary the boost required for the fuel needed to maintain load.
At higher revs and supercharger at full boost it opens more to bleed excess air to maintain max boost pressure (same as wastegate in principle)

Bazzle

 

[Glenn Smith]

Cheers, thats what I thought too.

 

[GarethM]

So is the purge valve is suposed to tick ?